Department of Chemistry and Center for Emerging Material and Advanced Devices and Center for Quantum Science and Engineering, National Taiwan University, Taipei 10617, Taiwan.
J Chem Phys. 2017 Nov 21;147(19):194106. doi: 10.1063/1.4999073.
A simple molecular orbital treatment of local current distributions inside single molecular junctions is developed in this paper. Using the first-order perturbation theory and nonequilibrium Green's function techniques in the framework of Hückel theory, we show that the leading contributions to local current distributions are directly proportional to the off-diagonal elements of transition density matrices. Under the orbital approximation, the major contributions to local currents come from a few dominant molecular orbital pairs which are mixed by the interactions between the molecule and electrodes. A few simple molecular junctions consisting of single- and multi-ring conjugated systems are used to demonstrate that local current distributions inside molecular junctions can be decomposed by partial sums of a few leading contributing transition density matrices.
本文发展了一种简单的分子轨道处理方法，用于研究单分子结内部的局域电流分布。我们使用 Hückel 理论框架中的一级微扰理论和非平衡格林函数技术，表明局域电流分布的主要贡献与跃迁密度矩阵的非对角元素成正比。在轨道近似下，局域电流的主要贡献来自于少数由分子与电极之间的相互作用混合的主导分子轨道对。本文使用了一些由单环和多环共轭体系组成的简单分子结来证明，分子结内部的局域电流分布可以通过少数主要贡献跃迁密度矩阵的部分和来分解。
